Kyuichi Maruyama

Acoustic emission evaluation of an arch dam during construction cooling and grouting

Abstract Acoustic emission (AE) monitoring was conducted in order to ensure safe construction of an arch dam under severe climate conditions. The AE was detected during the secondary cooling in the winter time while the construction was suspended due to low temperature and heavy snow. In the spring time just before the construction restarted, AE was monitored during grouting into a joint of dam blocks. A multi-channel digital signal processing system was used to perform a quantitative AE waveform analysis based on the moment tensor analysis as well as the conventional AE parameter measurement. Low frequency AE sensors (15 kHz resonant) were employed to detect AE signals since the signals with ordinary frequencies attenuate greatly during the propagation in concrete of the dam. Twelve sensors were buried from the dam surface and four were mounted on the corridor floor inside the dam. Neither critical AE activity nor intense AE cluster were observed in the AE monitoring. Thus, it was confirmed that the dam was safe during both the secondary cooling and the grouting. The AE monitoring was proven to be very useful for the safety inspection of a dam under construction in severe conditions.

NUMERICAL SIMULATION OF LONG-TERM BEHAVIOUR OF CONCRETE STRUCTURES WITH EXTERNALLY BONDED CONTINUOUS FIBRE SHEET

ABSTRACT A numerical simulation of long-term behaviour of concrete structures retrofitted with externally-bonded continuous fibre sheet is presented. Continuous fibre sheet can improve not only mechanical performance of an existing concrete structure but also its durability. The effectiveness of continuous fibre sheet as a surface insulator was quantified by laboratory tests. Based on this, case studies of numerical service-life simulation of concrete structures with continuous fibre sheet under corrosive environment are demonstrated. The results imply that continuous fibre sheet can extend service-life of concrete structures.